Communications system radio coverage reconfiguration based on available capacity of a compensation cell

ABSTRACT

In a cellular communication system, a coverage area configuration transition is performed when it is determined that the resources allocated to a compensation service area have sufficient available capacity to serve one or more UE devices being served by an energy saving service area, A coverage area configuration transition includes reducing the coverage of an energy saving service area and expanding the coverage of a compensation service area. A compensation communication station providing the compensation service area sends a request for a coverage area configuration transition to an energy saving communication station. The energy saving communication station may reject the coverage area configuration transition or may accept it and send an expansion notification to the compensation communication station, where the notification at least indicates that the compensation service area can be expanded.

PRIORITY

The present application claims priority to Provisional Application No.61/864,474 entitled “Methods for Managing Resources for TransitionsBetween Cell Coverage Configurations”, filed Aug. 9, 2013, assigned tothe assignee hereof, and hereby expressly incorporated by reference.

FIELD

The invention generally relates to wireless communications and moreparticularly to apparatuses, systems, and methods for changingcommunications systems radio coverage configuration based on availablecapacity of one or more compensation cells.

BACKGROUND

Many wireless communication systems employ transceiver stations or radioheads to provide service within geographical service areas, where theboundaries of a service area are determined by the radio coverage of itsassociated transceiver station. Wireless service is provided to userequipment (UE) devices over radio frequency carriers (carriers) withineach service area, where a carrier is the modulated waveform thatconveys the physical channels as specified by the associated wirelesstechnology standard. These service areas are sometimes referred to as“cells”.

Although the term “cell” sometimes refers to the geographical area wheremultiple uplink and downlink resources (e.g., pairs of uplink anddownlink carriers) are used, increasingly the term. “cell” is used torefer to the geographical service area where single uplink resource anda single downlink resource are used to communicate with the UE devices.For example, where Time Division Duplex (TDD) is used, a singlefrequency may be used for uplink and downlink at different times withinthe “cell”. Where Frequency Division Duplex (FDD) is used, a singleuplink/downlink frequency pair (one uplink frequency and one downlinkfrequency) is used within a “cell”.

As discussed herein, one or more resources (carrier pairs) may be usedin a service area. As a result, a service area may be a single cell ormay contain multiple cells. In one common arrangement, each service areais adjacent to several other service areas to provide ubiquitouscoverage over a large geographical area

Adjacent service areas may overlap slightly, but, for the followingdiscussion, no service areas provide service within the samegeographical area. In many situations, there may be an advantage'todynamically change the configuration of the service areas, such as byselectively reducing the size of some service areas and expanding thesize of one or more other service areas to provide service within thearea previously serviced by the service areas that were reduced. Suchdynamic coverage area configuration transitions may allow for moreefficient operation of the system.

For example, a service area with only a small number of UE devices maybe reduced to zero by deactivating its associated transceivers, and anadjacent service area that is serving several UE devices but hasavailable capacity may be expanded to provide radio coverage for the UE,devices previously contained in the reduced service area. Therefore, aservice area that is reduced may be referred to as an energy savingservice area since the energy consumed by its associated transceivers isreduced or eliminated, and a service area that is reduced to zero may bereferred to as a deactivated service area A service area that isexpanded in cooperation with a service area that is reduced may bereferred to, as compensation service area since its service area isexpanded to compensate for a service area that is reduced.

UE devices being served by an energy saving service area may lose theirconnection with the network if they are not handed over to anotherservice area before the energy saving service area is deactivated. Ifthe energy saving service area and the compensation service area operateon the same frequency resources, UE devices being served by an energysaving service area may lose their connection with the network if thecompensation service area is expanded before the UE devices are handedover to another service area because of the interference between theenergy saving service area and the compensation service area. Asdiscussed below, management techniques are needed to control the dynamiccoverage area configuration transitions.

SUMMARY

In a cellular communication system, a coverage area configurationtransition is performed when it is determined that the resourcesallocated to a compensation service area have sufficient availablecapacity to serve one or more UE devices being served by an energysaving service area In reconfiguring the coverage areas of the system,the compensation service area is expanded to cover at least a portion ofan energy saving service area of an energy saving cell and the energysaving service area is at least partially deactivated. A compensationcommunication station providing the compensation service area sends arequest for a coverage area configuration transition to an energy savingcommunication station, and the energy saving communication station mayreject the coverage area configuration transition or may accept it andsend an expansion notification to the compensation communicationstation, where the notification at least indicates that the compensationservice area can be expanded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of coverage areas in a cellular communicationsystem.

FIG. 2 is an illustration of a coverage transition where the energysaving service area (ES SA) is deactivated and the compensation servicearea (Comp. SA) is expanded to provide wireless service within thegeographical region of the energy saving service area.

FIG. 3 includes illustrations of a coverage area transition where thecompensation service area is expanded to cover more than one energysaving service area.

FIG. 4 is a message flow diagram between the compensation communicationstation, the energy saving communication station, and the UE devices.

FIG. 5 is a method of operating the system shown in FIG. 1.

DETAILED DESCRIPTION

In a cellular communication system, a coverage area configurationtransition is performed when it is determined that the resourcesallocated to a compensation service area have sufficient availablecapacity to serve one or more UE devices being served by an energysaving service area. In reconfiguring the coverage area of the system,the compensation service area (e.g., compensation communication stationcoverage area) is expanded to include at least a portion of an areacovered by the energy saving communication station. For example, theexpanded compensation service area would cover an energy saving servicearea of an energy saving cell and the energy saving service area isdeactivated.

FIG. 1 is an illustration of coverage areas in a cellular communicationsystem 100 where coverage area transitions are based on the availablecapacity of a compensation cell. For the example of FIG. 1, an energysaving communication station provides wireless service within ageographical service area represented by a circular area of an energysaving cell and a compensation communication station provides wirelessservice within a geographical service area represented by a circulararea of a compensation cell. In typical implementations of the cellularcommunication system 100, several adjacent cells cover largergeographical regions. In the interest of brevity and clarity, however,FIG. 1 shows only two cells 104, 106. The circular shapes representingthe service areas of the cells generally illustrate the relationshipsbetween the cells and do not necessarily depict the actual shapes of theservice areas. The coverage area configuration transition managementtechniques discussed with reference to FIG. 1 may be applied to numerouscoverage area configuration transition scenarios. For example, severalenergy saving cells may be deactivated and a compensation cell may beexpanded to cover the geographical service areas of the multiple energysaving cells in accordance with the techniques discussed herein. Thecells may have any of several shapes and sizes.

Communication stations 108, 112 transmit and receive wireless signals toprovide the cells 104, 106. Each communication station 108, 112, whichalso may be referred to as an access node, access point, eNodeB, eNB,base station, and other terms, includes a transceiver and stationcontroller. The controller in each communication station is configuredto perform the various methods and operations described herein. Thetransceiver, or radio head, is typically collocated with the stationcontroller although, in some situations, the station controller may bephysically separated from the radio head. The radio head at leastincludes radio frequency (RF) transceiver equipment such as antennas,transmitters, and receivers, for transmitting and receiving wirelesssignals. Typically, radio heads do not include higher level processingand control functions which are performed by the associated stationcontroller. For the illustration of FIG. 1, the radio heads are near astation controller where both the radio head and the controller may beimplemented within a single apparatus. Since the location, shape, andsize of the cell is determined at least in part by wireless transmissionand reception with the communication station, the cell's location andcoverage area is determined by the location and operation of the radiohead. The compensation communication station 108 provides thecompensation cell 104 and an energy saving communication station 112provides the energy saving cell 106. Each communication station 108,112, therefore, provides wireless communication services to wirelesscommunication user equipment devices (UE devices) 114, 116, 118 withinthe cell where each cell covers a geographical service areaCommunication stations typically provide several cells, but in theinterest of brevity and clarity, communication stations 108 and 112provide one cell and the full radio and data processing capacity ofcommunication stations 108 and 112 are applied to the service of thecell they provide. Accordingly, for the example shown in FIG. 1, theavailable capacity of a cell is equivalent to the available capacity ofthe communication station that provides the cell. As discussed herein, acommunication station includes the equipment such as a stationcontroller and radio head that provides a single cell. Accordingly, acommunication station can be configured or adjusted to establish thesize and shape of the service area of the cell. Several communicationstations are typically interconnected through a backhaul (not shown) andto a network (not shown) to provide several service areas to cover largeareas. The backhaul may include any combination of wired, optical,and/or wireless communication channels. For the examples herein, thenetwork includes the functionality of the Mobility Management Entity(MME) and the Packet Gateway (P-GW).

A cellular communication system is typically required to adhere to acommunication standard or specification. The communication specificationdefines at least a data channel and a control channel for uplink anddownlink transmissions and specifies at least some timing and frequencyparameters for physical downlink control channels from a base station toa wireless communication device. The Third-Generation PartnershipProject Long-Term Evolution (3GPP LTE) communication specification is aspecification for systems where communication stations (eNodeBs) provideservice to wireless communication devices (UE devices) using orthogonalfrequency-division multiplexing (OFDM) on the downlink andsingle-carrier frequency-division multiple access (SC-FDMA) on theuplink. Although the techniques described herein may be applied in othertypes of communication systems, the exemplary systems discussed hereinoperate in accordance with an FDD 3GPP LTE communication specification.

Therefore, for the examples herein, the compensation communicationstation 108 includes a wireless transceiver that transmits downlinksignals 120 to one or more UE devices 114 within the compensation cell104 in accordance with 3GPP LTE and receives uplink signals 122 from oneor more UE devices 114 within the compensation cell 104 in accordancewith 3GPP LTE. The energy saving communication station 112 includes awireless transceiver that transmits downlink signals 126 and 130 to oneor more UE devices 116, 118 within the energy saving cell 106 inaccordance with 3GPP LTE and receives uplink signals 124 and 128 fromone or more UE devices 116, 118 within the energy saving cell 106 inaccordance with 3GPP LTE.

The User Equipment (UE) devices 114, 116, 118 may be referred to asmobile devices, wireless devices, wireless communication devices, andmobile wireless devices, and UEs, as well as by other terms. Thewireless communication devices include electronics and code forcommunicating with communication stations (eNBs) and, in some cases,with other devices including other UE devices. The UE devices includedevices such as smart phones, cell phones, personal digital assistants(PDAs), wireless modem cards, wireless modems, televisions with wirelesscommunication electronics, and laptop and desktop computers, as well asother devices. The combination of wireless communication electronicswith an electronic device, therefore, may form a wireless communicationdevice. For example, a wireless communication device may include awireless modem connected to an appliance, computer, or television.

In some instances, the compensation communication station 108 uses thesame frequency channel to provide the compensation cell 104 as theenergy saving communication station uses to provide the energy savingcell 106. For the example of FIG. 1 the same set of downlink/uplinkfrequency channel pairs may be assigned for the compensation cell 104and the energy saving cell 106. In the cell configuration shown in FIG.1, communications in the compensation cell do not interfere withcommunications in energy saving cell 106 when both cells use the samefrequency channel since the service areas of the cells do not overlap.When the compensation cell and energy saving cell use the same frequencychannel and the service area of the compensation cell is expanded asdiscussed below, the compensation cell will interfere with the UEdevices served by the energy saving cell if not managed in some manner.

First, the compensation communication station 108 determines a trafficload of the compensation cell. As used herein, the term “traffic load”generally refers to an amount of communications resources of aparticular cell that are being used by the UE devices that are beingserved by the cell. Traffic load can be expressed in an absolute termsor as a measurement relative to the total resources (e.g., capacity) ofthe cell.

Regardless of how the traffic load is expressed, if the traffic load ofthe compensation cell is below a first threshold level, the traffic loadof the energy saving cell is determined. More specifically, thecompensation communication station 108 transmits a request 132 for thetraffic load of the energy saving communication station 112. The energysaving communication station responds by transmitting the traffic loadindicator 134 that is indicative of the traffic load of the energysaving communication station to the compensation communication station108. Based at least on the traffic load of the energy saving cell andthe available capacity of the compensation cell, the compensationcommunication station 108 determines whether the compensation cell canserve the UE devices 116, 118 being served by the energy savingcommunication station 112 if the compensation service area were to beexpanded to include the energy saving service area. When determiningwhether the compensation cell can serve the traffic load of the energysaving cell, the compensation communication station may take intoconsideration the amount of the energy saving cell's traffic load thatcould be transferred to other cells. This information could be obtainedfrom the energy saving communication station or from a centralizedtraffic management server, or it might be determined by the compensationcommunication station based on traffic load reports received from othercommunication stations. In response to a determination that thecompensation cell can serve the UE devices 116, 118 being served by theenergy saving cell, the compensation communication station 108 initiatesa transition of the radio coverage area configuration.

In the example shown in FIG. 1, the coverage area configurationtransition consists of expanding the compensation service area, handingover the UE devices being served by the energy saving cell, anddeactivating the energy saving cell. In general, all of the UE devicesbeing served by the energy saving cell are handed over to one or morecompensation cells (or neighboring cells that do not expand theircoverage area) before the energy saving cell reduces the amount ofenergy being used, and the compensation coverage area is expanded toinclude the entire area of the energy saving service area. However, inother instances, the energy saving cell's activity may only be partiallyreduced and a compensation service area may be expanded to include onlya part of the energy saving service area. The energy saving cell mayhand over one or more UE devices and still continue to serve one or moreremaining UE devices. When the energy saving cell hands over all of itsUE devices, the reduction of energy will generally include switching offor deactivating the energy saving cell 106. In other circumstances, thereduction of energy could include: reducing the size of the service areabeing served by the energy saving cell 106, reducing the broadcaststrength of the signals 126, 130 being transmitted by the energy savingcommunication station 112, and/or reducing the number of UE devicesbeing served by the energy saving cell 106.

FIG. 2 is an illustration of a coverage transition where the energysaving service area (ES SA) 106 is deactivated and the compensationservice area (Comp. SA) 104 is expanded to provide wireless servicewithin the geographical region of the energy saving service area 106. Inthe example of FIG. 2, a coverage transition within the system of FIG. 1is shown progressing through three stages. In the interests of clarityand brevity, two UE devices 116, 118, are shown in the example.

In the first stage 202, the UE devices 116, 118 are communicating overwireless communication links 204, 206 with the communication station 112of the energy saving service area 106. For the example, the UE devices116, 118 are at least receiving control signals and may also betransmitting control signals and exchanging data with the communicationstation 112 prior to the coverage transition. The coverage transitionmay be initiated in response to a determination that the energy savingservice area 106 should be deactivated and the compensation service area104 should be expanded. Such a determination may be based on any numberof several factors and circumstances where some examples include theresource load on the energy saving service area 106 and the compensationservice area 104. For example, the resource load of the energy savingservice area may at least partly be based on the amount of time andfrequency resources being used by all of the UE devices 116, 118 withinthe service area. The determination for deactivating the energy savingservice area 106 may be based on whether the resources allocated to thecompensation service area 104 have sufficient available capacity toprovide service to the UE devices 116, 118 within the ES service area106. As another example, the determination for deactivating an energysaving service area 106 may be based on a particular time, day, month,etc., where an operator has determined that the traffic load at thistime can be managed without the energy saving service area 106. Inresponse to the determination that the energy saving service area 106should be deactivated, the coverage transition is initiated.

In FIG. 2, when it is determined that the compensation cell's trafficload may be sufficiently low to allow the deactivation of the energysaving cell 106, the compensation communication station 108 obtains thecurrent traffic load of the energy saving cell 106. The compensationcommunication station 108 may already have this information because ofpreviously received traffic load information or it may request theinformation based on existing methods. When the level of the trafficload of the energy saving cell 106 does not exceed the availablecapacity of the resources allocated to the compensation coverage area104, the compensation communication station 108 sends a message to theenergy saving communication station 112 to request a cell coverageconfiguration transition. The energy saving communication station 112sends a response message that indicates whether the request is acceptedor not For the purpose of this illustration, the cell coverageconfiguration transition would consist of the expansion of the coveragearea 104 of the compensation cell to include the energy saving coveragearea 106 and the deactivation of the energy saving service area 106.

When the compensation communication station 108 receives a responsemessage from the energy saving communication station 112 with an“accept” indication, the coverage transition may be initiated, which isthe second stage 208. The compensation communication station 108initiates the expansion of the compensation service area and the energysaving communication station 112 initiates the handover procedures forthe UE devices 116, 118 currently receiving wireless service from theenergy saving communication station 112. The UE devices 116, 118 arehanded over from the energy saving cell to other cells according to thetypical LTE handover procedures. UE devices 116, 118 may be handed overto the compensation cell 104 when the compensation cell's coverage ofthe energy saving service area 106 allows it to be a suitable handovertarget for the UE.

After the compensation cell expansion is complete, the compensationcommunication station 108 notifies the energy saving communicationstation 112. After the energy saving communication station 112 receivesnotification that the compensation cell expansion is complete and all ofthe UE devices 116, 118 are handed over to other cells, at the thirdstage 210 of the transition procedure, the energy saving service area106 is deactivated. The circle representing the energy saving servicearea 106 is shown with a dashed line to indicate that the cell is nolonger active. As a result, the energy saving communication station(eNB) 112 does not provide wireless service within the energy savingservice area 106 by transmitting or receiving wireless signals. For theexample herein, the energy saving communication station 112 is turnedoff and consumes little or no power, and the UE devices 116, 118 arecommunicating over wireless communication links 212, 214 with thecompensation communication station 112 of the expanded compensationservice area 104.

FIG. 3 includes illustrations 300, 301 of a coverage area transitionwhere the compensation service area is expanded to cover more than oneenergy saving service area. The circular shapes representing the serviceareas generally illustrate the relationships between the service areasand do not necessarily depict the actual shapes of the service areas. Inaddition, the service areas may overlap in some regions more than inother regions. The open areas shown between the circular shaped serviceareas in the figure do not necessarily indicate that no service isavailable in these areas and are merely a product of illustrationutilizing simple shapes to represent a more complicated relationshipbetween service areas. Further, the service areas may contain. holes ofcoverage where service is unavailable. In the interests of clarity andbrevity, such features are not illustrated in the figures.

For the example of FIG. 3, the region 102 includes the geographicalareas of several smaller service areas 104, 106, 302, 304, 306, 308, 310including the compensation service area 104 and three energy savingservice areas 106, 302, 304. In state 300 before the compensation areais expanded, the energy saving service areas 106, 302, 304 have coverageareas adjacent to the compensation service area 104. In state 301 afterthe compensation service area is expanded, the compensation service area312 has a coverage area that includes the original coverage area of thecompensation service area 104 and at least portions of the coverageareas of the energy saving service areas 106, 302, 304. The expandedcompensation service area 312, therefore, is the compensation servicearea 104 with a larger coverage area The energy saving service areas areshown with dashed lines in the coverage state 301 to illustrate that theservice areas have been deactivated. The coverage area transitionprocedure for multiple energy saving service areas is similar to thetransition procedure for a single energy saving service area discussedabove. In one example, the compensation service area expands to covereach energy saving service area serially. In other words, thecompensation service area is expanded to cover a first energy savingservice area before a second energy service area. In such an example,all UE devices in the first energy saving service area are handed overto the compensation service area, the compensation service area isexpanded to cover the first energy saving service area, and the UEdevices are transferred to the compensation service area prior to theprocedure being performed for next energy saving service area in theexamples discussed below, however, the compensation service area isexpanded to cover multiple energy saving service area areas in a singlecoverage area transition procedure. In this example, all UE devices fromall energy saving service areas are handed over to the compensationservice area, the compensation service area is expanded, and all the UEdevices complete the handovers to the compensation service area. In somecircumstances, some UE devices may be transferred to neighboring smallservice areas (306, 310) instead of the compensation service area. Inthese instances, the small service areas 306, 310 may act as additionalcompensation communication stations and may remain the same size or mayexpand/reduce their respective compensation service areas, as needed.

In some situations, a first compensation service area (e.g., firstcompensation communication coverage area) is only expanded to cover aportion of the energy saving service area, and one or more additionalcompensation communication stations each expand their respectivecoverage areas to include any portion of the energy saving service areathat is not covered by the expanded first compensation communicationstation coverage area.

FIG. 4 is a message flow diagram 400 between the compensationcommunication station 108, the energy saving communication station 112,and the UE devices 116, 118. For the example, the communication stationsare eNBs that communicate through the backhaul over an X2 link inaccordance with LTE communication standards. Other communicationtechniques can be used in some circumstances. More specifically, thecommunication stations could communicate wirelessly in somecircumstances.

For the example shown in FIG. 4, in response to determining that thetraffic load of the compensation cell is below a first threshold level,the compensation communication station (compensation cell eNB) 108 sendsa request 402 to the energy saving communication station (ES eNB) 112for the traffic load of the energy saving cell. In response to therequest, the energy saving communication station 112 transmits 404 atraffic load indicator (e.g., indicator 134 from FIG. 1) indicative ofits current traffic load to the compensation communication station 108.Based at least on the traffic load of the energy saving cell and theavailable capacity of the compensation cell, the controller of thecompensation communication station 108 determines whether thecompensation cell can serve the UE devices 116, 118 that are beingserved by the energy saving communication station 112.

If it is determined that the compensation communication station 108 canserve the UE devices 116, 118 being served by the energy saving cell,the compensation communication station 108 sends a request to the energysaving communication station 112 to initiate a transition of the cellcoverage configuration for the energy saving cell. In the example shownin FIG. 4, this request is a Cell Status Change Request 406. The energysaving communication station 112 sends a response to the compensationcommunication station 108 accepting or rejecting the request to initiatea transition of the cell coverage configuration for the energy savingcell. In this example, the response is a Cell Status Change Response408. The Cell Status Change Response 408 is an example of the ExpansionNotification and indicates to the compensation communication station 108that the compensation service area can be expanded. In one example, theCell State Change messages 406/408 are part of a dedicated procedure forthis feature that is added to a standard specification. In othercircumstances, the Cell State Change messages 406/408 functions may beincorporated into messaging structures and procedures currently definedby a communication, standard, such as the Load Management or eNBConfiguration Update procedures contained in the LTE communicationstandard. In either case, modifications of the LTE communicationstandard can facilitate the communication.

A part of the transition of the cell coverage configuration is that thecompensation cell is reconfigured such that its coverage area isexpanded to include the coverage area being served by the energy savingcell. The expansion of the compensation service area is initiated by thecompensation communication station 108 after receiving the Cell StatusChange Response 408 with an indication that the energy savingcommunication station 112 accepts the request for a transition of thecell coverage configuration for the energy saving cell. The compensationcommunication station 108 increases transmission power and performsother known techniques for expanding the compensation service area tocover the energy saving service area For example, techniques such asantenna tilting and antenna beam forming may be used to provide anexpanded service area of the compensation cell that covers the originalservice area of the energy saving service area as well as the originalservice area of the compensation service area.

Where multiple energy saving service areas are deactivated, thecompensation service area is expanded to cover those service areas. Inone example, the parameters for establishing the expanded coverage areaare determined at the time of equipment deployment. For example, signalquality measurements may be made and the parameters may be determinedusing the, signal measurements at the time of or after equipmentinstallation. Accordingly, the compensation communication stationapplies stored values or values it has received from an Operations andMaintenance (OAM) system to expand the service area to cover the areasof the energy saving service areas that have been deactivated.

The UE devices 116, 118 are handed over from the energy saving cell toother cells according to the typical LTE handover procedures. A UEdevice may be handed over to the compensation cell when the compensationcell's coverage of the energy saving service area allows it to be asuitable handover target for the UE. As illustrated in FIG. 4, handovermessages 410 for the first UE device 116 are exchanged between thecommunication stations 108, 112 and handover messages 412 for the nth UEdevice 116 are exchanged between the communication stations 108, 112.When all of the UE devices 116, 118 are handed over to other cells andthe compensation cell has completed its coverage expansion to includethe energy saving service area, the energy saving service area 106 isdeactivated. As discussed herein, a service area is “deactivated” whenit no longer transmits downlink signals to UE devices and does notreceive or process uplink signals from UE devices. Therefore, adeactivated service area cannot provide wireless service to UE devices.The communication station that provides the energy saving service areastill includes active functions and is not turned off. For example, thecommunication station is still capable of communicating with othercommunication stations and/or the network.

In some circumstances, a communication station configuration updatemessage may be sent from the energy saving communication station 112 toother communications stations indicating that the energy saving servicearea is no longer active. The other communication stations include atleast the neighbor stations of the energy saving service area and mayinclude other communication stations that require information regardingthe status of the energy saving service area For example, thisfunctionality could be added to the LTE X2 interface eNB ConfigurationUpdate message that communication stations use to notify othercommunication stations about configuration changes of their serviceareas (cells).

Also, in some circumstances, a communication station configurationupdate message may be sent from the compensation communication station108 to the other communications stations indicating that thecompensation service area has been expanded. The other communicationstations include at least the neighbor stations of the energy savingservice area and the compensation service area and may include othercommunication stations that require information regarding the status ofthe compensation service area. For example, this functionality could beadded to the LTE X2 interface eNB Configuration Update message thatcommunication stations use to notify other communication stations aboutconfiguration changes of their service areas.

FIG. 5 illustrates a method 500 of operating system 100. At step 502, acontroller of the compensation communication station 108 determines atraffic load of the compensation cell. At step 504, if the traffic loadof the compensation communication station 108 is below a first thresholdlevel, the compensation communication station 108 transmits a request132 for the traffic load of the energy saving communication station 112.The energy saving communication station 112 responds by transmitting thetraffic load indicator 134 indicative of the traffic load of the energysaving communication station 112 to the compensation communicationstation 108.

At step 506, based at least on the traffic load of the energy savingcell and the available capacity of the compensation cell, thecompensation communication station 108 determines if the compensationcell can serve the UE devices 116, 118 being served by the energy savingcell. In some circumstances, determining whether the compensation cellcan serve one or more of the UE devices 116, 118 being served by theenergy saving cell includes determining whether the traffic load of theenergy saving cell is less than or equal to the available capacity ofthe compensation cell.

If it is determined that the compensation cell cannot serve the UEdevices 116, 118 being served by the energy saving cell, thecompensation communication station 108 transmits a request to the energysaving communication station 112 that the energy saving communicationstation 112 transmits a traffic load report or other indication to thecompensation communication station 108 when the traffic load of energysaving cell falls below a second threshold level.

In some situations, the determination that the compensation cell cannotserve the UE devices 116, 118 being served by the energy saving cellincludes determining that the traffic load of the energy saving cell ismore than a capacity threshold based on the available capacity of thecompensation cell. For example, the capacity threshold could be 80% ofthe available capacity of the compensation cell. Of course, the capacitythreshold could be any suitable threshold amount, based on systemcapabilities, requirements, expected traffic demands, and any otherpertinent criteria. When it is determined that the traffic load of theenergy saving cell is more than the capacity threshold based on theavailable capacity of the compensation cell, the compensationcommunication station 108 transmits the request to the energy savingcommunication station 112 that the energy saving communication station112 transmits a report to the compensation communication station 108when the traffic load of the energy saving cell falls below a secondthreshold level. In some situations, the second threshold level may beupdated as the traffic load of the compensation cell changes.

Regardless of the exact method used to determine that the compensationcell cannot serve the UE devices 116, 118 being served by the energysaving cell, the energy saving communication station 112 transmits, atstep 508, the requested report to the compensation communication station108 when the traffic load of the energy saving cell falls below thesecond threshold level. In response to a determination that thecompensation cell can serve the UE devices 116, 118 being served by theenergy saving cell and the energy saving communication station 112accepting the request for a transition of the cell coverageconfiguration for the energy saving cell, the compensation cell isreconfigured, at step 510, such that its coverage is expanded to includethe coverage area being served by the energy saving cell. The UE devices116, 118 are handed over from the energy saving cell to other cellsaccording to the typical LTE handover procedures. A UE device may behanded over to the compensation cell when the compensation cell'scoverage of the energy saving service area allows it to be a suitablehandover target for the UE. When all of the UE devices 116, 118 arehanded over to other cells and the compensation cell has completed itscoverage expansion to include the energy saving service area, the energysaving service area 106 is deactivated. In the example shown in FIG. 1,the reduction of energy includes switching off or deactivating theenergy saving cell 106. In other situations, the reduction of energyincludes: reducing the size of the service area being served by theenergy saving cell 106, reducing the broadcast strength of the signals126, 130 being transmitted by the energy saving communication station112, and/or reducing the number of UE devices being served by the energysaving cell 106.

Clearly, other modifications and manners of practicing this inventionwill occur readily to those of ordinary skill in the art in view ofthese teachings. The above description is illustrative and notrestrictive. This invention is to be limited only by the followingclaims, which include all such modifications and manners of practicewhen viewed in conjunction with the above specification and accompanyingdrawings. The scope of the invention should, therefore, be determinednot with reference to the above description, but instead should bedetermined with reference to the appended claims along with their fullscope of equivalents.

1. A method comprising: determining a traffic load of a firstcompensation communication station, if the traffic load of the firstcompensation communication station is below a first threshold level,determining a traffic load of an energy saving communication station;determining, based at least on the traffic load of the energy savingcommunication station and an available capacity of the firstcompensation communication station, whether the first compensationcommunication stator can serve one or more user equipment devices (UEdevices) being served by the energy saving communication station; inresponse to determining that the first compensation communicationstation can serve one or more UE devices being served by the energysaving communication station, reconfiguring the first compensationcommunication station such that the first compensation communicationstation can serve the one or more UE devices being served by the energysaving communication station; handing over at least one of the UEdevices from the energy saving communication station to the firstcompensation communication station; and reducing an amount of energyused by the energy saving communication station.
 2. The method of claim1, wherein the determining whether the first compensation communicationstation can serve one or more UE devices being served by the energysaving communication station comprises: determining whether the trafficload of the energy saving communication station is less than or equal tothe available capacity of the first compensation communication station.3. The method of claim 1, wherein reconfiguring the first compensationcommunication station comprises: expanding a first compensationcommunication station coverage area to include at least a portion of anarea covered by the energy saving communication station.
 4. The methodof claim 3, wherein expanding the first compensation communicationstation coverage area comprises: expanding the first compensationcommunication station coverage area to include all of the area coveredby the energy saving communication station.
 5. The method of claim 3,wherein one or more additional compensation communication stationsexpand their respective coverage areas to include any portion of thearea covered by the energy saving communication station that is notcovered by the expanded first compensation communication stationcoverage area.
 6. The method of claim 1, wherein handing over at leastone of the UE devices comprises: handing over all of the UE devicesbeing served by the energy saving communication station to the firstcompensation communication station.
 7. The method of claim 1, whereinreducing the amount of energy used by the energy saving communicationstation comprises: deactivating the energy saving communication station.8. The method of claim 1, further comprising: if the traffic load of theenergy saving communication station is more than a capacity thresholdbased on the available capacity of the first compensation communicationstation, requesting that the energy saving communication stationtransmits a report to the first compensation communication station whenthe traffic load of the energy saving communication station falls belowa second threshold level; and transmitting the requested report to thefirst compensation communication station when the traffic load of theenergy saving communication station falls below the second thresholdlevel.
 9. The method of claim 1, further comprising: transmitting arequest to initiate a transition of a cell coverage configuration,transmitting a response to the request to initiate a transition of thecell coverage configuration; and if the response is an acceptance,initiating a transition of the cell coverage configuration.
 10. Acompensation communication station, comprising: a controller configuredto determine a traffic load of the compensation communication station;and a transmitter configured to transmit a request for a traffic load ofan energy saving communication station if the traffic load of thecompensation communication station is below a first threshold level,wherein the controller is further configured to: determine, based on atleast the traffic load of the energy saving communication station and anavailable capacity of the compensation communication station, whetherthe compensation communication station can serve one or more userequipment devices (UE devices) being served by the energy savingcommunication station, in response to determining that the compensationcommunication station can serve one or more UE devices being served bythe energy saving communication station, reconfigure the compensationcommunication station such that the compensation communication stationcan serve one or more UE devices being served by the energy savingcommunication station, and receive at least one of the UE devices beinghanded over from the energy saving communication station to thecompensation communication station.
 11. The compensation communicationstation of claim 10, wherein the controller is configured to determinethat the compensation communication station can serve one or more UEdevices being served by the energy saving communication station if thetraffic load of the energy saving communication station is less than orequal to the available capacity of the compensation communicationstation.
 12. The compensation communication station of claim 10, whereinthe controller is further configured to: expand a compensationcommunication station coverage area to include at leas a portion of anarea covered by the energy saving communication station.
 13. Thecompensation communication station of claim 12 wherein the controller isfurther configured to: expand the compensation communication stationcoverage area to include a the area covered by the energy savingcommunication station.
 14. The compensation communication station ofclaim 10, wherein the controller is further configured to: receive allof the UE devices being handed over from the energy saving communicationstation to the compensation communication station.
 15. The compensationcommunication station of claim 10, wherein the controller is furtherconfigured to: if the traffic load of the energy saving communicationstation is more than a capacity threshold based on the availablecapacity of the compensation communication station, request that theenergy saving communication station transmits a report to thecompensation communication station when the traffic load of the energysaving communication station falls below a second threshold level.
 16. Asystem, comprising: a compensation communication station, comprising: acontroller configured to determine a traffic load of the compensationcommunication station, and a transmitter; and an energy savingcommunication station, comprising: a receiver configured to receive arequest, transmitted by the compensation communication station, for atraffic load of the energy saving communication station if the trafficload of the compensation communication. station is below a firstthreshold level, and a transmitter configured to transmit the trafficload of the energy saving communication station to the compensationcommunication station, wherein the controller is further configured to:determine, based on at least the traffic load of the energy savingcommunication station and an available capacity of the compensationcommunication station, whether the compensation communication stationcan serve one or more user equipment devices (UE devices) being servedby the energy saving communication station, in response to determiningthat the compensation communication station can serve one or more UEdevices being served by the energy saving communication station,reconfigure the compensation communication station such that thecompensation communication station can serve one or more UE devicesbeing served by the energy saving communication station, and receive atleast one of the UE devices being handed over from the energy savingcommunication station to the compensation communication station.
 17. Thesystem of claim 16, wherein the controller is configured to determinethat the compensation communication station can serve one or more UEdevices being served by the energy saving communication station if thetraffic load of the energy saving communication station is less than orequal to the available capacity of the compensation communicationstation.
 18. The system of claim 16, wherein the controller is furtherconfigured to expand a compensation communication station coverage areato include at least a portion of an area covered by the energy savingcommunication station.
 19. The system of claim 18, wherein thecontroller is further configured to: expand the compensationcommunication station coverage area to include all of the area coveredby the energy saving communication station.
 20. The system of claim 18,wherein one or more additional compensation communication stationsexpand their respective coverage areas to include any portion of thearea covered by the energy saving communication station that is notcovered by the expanded compensation communication station coveragearea.
 21. The system of claim 16, wherein the controller is furtherconfigured to: receive all of the UE devices being handed over from theenergy saving communication station to the compensation communicationstation.
 22. The system of claim 16, wherein the energy savingcommunication station is configured to deactivate after handing over atleast one of the UE devices.
 23. The system of claim 16, wherein thecontroller is further configured to: if the traffic load of the energysaving communication station is more than a capacity threshold based onthe available capacity of the compensation communication station,request that the energy saving communication station transmits a reportto the compensation communication station when the traffic load of theenergy saving communication station falls below a second thresholdlevel; and receive the requested report when the traffic load of theenergy saving communication station falls below the second thresholdlevel.